1. Field of the Invention
The present invention relates to convertible sofas which can be converted into a bed and more particularly that which can be converted into a lower and upper bed structure.
2. Description of the Prior Art
The convertible sofas available today consist generally of the lower bed type which have a seat and backrest member arranged to fold up and move apart into a side by side lower bed. Some operate with the seat movable on slide members engaged in guided tracks to move forward while the backrest is movable by linkage members attached to the seat frame. This type of convertible sofa is normally used where floor space is not limited and the bed can be stretched out to clear wall structure furniture and the like. In the event that floor space is critical such as it is in the rear end of a motor van, for example, or a small bedroom it becomes a real problem to provide adequate bed space in such tight or cramped quarters. A built-in stationary upper and lower bunk structure may suffice in some instances but for the van, motor home or bedroom it is usually desirable to supplement the obvious bunk bed arrangement with a convertible sofa, couch, settee or a similar sitting room piece of furniture. On the other hand, to install a sofa which can be converted into a lower and upper bed in the limited space between the side walls of a van presents a real problem. A sofa consisting primarily of a seat and backrest structure does not normally include sufficient framework to house an internal linkage system required to raise the backrest structure high enough to make up an upper bed. Since this real problem continues to exist most attempts to solve the problem have resulted in essentially built-in types of convertible sofas which primarily rely on the side walls of the van to support and provide a part of the linkage system.
A settee-bed with backrest convertible to an upper bed is shown in U.S. Pat. No. 3,863,280 issued to Ned W. Minzelle which claims a settee mounted between fixed structural members at the head and foot of the bed. The fixed structural members in this device are fixed securely to the opposite side walls of the van. Further, the backrest structure is carried on brackets which are connected to the two structural members with the forward backrest member being part of a four bar linkage that is pivoted to the bracket. In raising to an upper level the forward backrest part swings up to a horizontal position in which it is against the rear wall of the van. At the same time the rearward backrest member which is suspended from a pair of hanger links swings forwardly underneath the forward backrest member and into upper bed position coplanar with the first backrest member.
The Mizelle device is essentially a built-in settee which pivots about upper and lower pivot connections on structural members secured to the side walls of a housing such as the rear end of a van. Accordingly, including the structural members, brackets and related linkage members being externally operated at the head and foot of the settee the hinged backrest members are raised to an upper bed position. In the raised upper bed position the backrest members are cantilever supported by the four bar linkage pivotably connected to the wall supported structural members. Therefore, with the weight of the sleeper applied on the upper bed the load is distributed in the form of tensile and compression stresses through the linkage to the side walls of the van rather than to the framework of the settee. Further, it appears that the Mizelle settee is largely custom made for the dimensions of the settee; linkage and structural members must be accurately established to conform to the inside space criteria of recreational vehicles. Since the Mizelle settee is not adjustable or portable it is somewhat limited in application to the recreational vehicle of a given class and does not adapt at all to a typical den or boys bedroom.
Another device similar to Mizelle's settee is shown in U.S. Pat. No. 3,311,932 issued to E. E. Ahola which discloses a berth-settee combination having a lower bunk fixed horizontally between opposite side walls of a housing again such as is found inside of a van. Ahola's settee comprises a backrest member which is equipped at each end with a forwardly disposed roller and a rearwardly disposed roller. There is a track attached to each of the opposite side walls and extending substantially horizontally thereacross and containing the corresponding forwardly disposed roller for support and guided travel. A second track is attached to each wall in a vertical directon and containing the rearwardly disposed roller therein for guided travel. The backrest member is then guided by its end roller in the horizontal and vertical tracks and raised from settee position to an upper bed position. Here again, Ahola's berth-settee is a built-in custom made structure and will not lend itself to wide usage.
In light of the above referenced prior art it is the object of the present invention to provide a portable sofa which will solve the aformentioned problems. The present invention is operably self-structured and independent of exterior structural support. The linkage means is confined within the framework of the sofa and structurally sufficient to support a heavy load applied on the upper bed and transfer the compression stresses resulting therefrom to the lower seat supporting structure. It can be manufactured readily and inexpensively with simple but effective means for converting a portable sofa into a lower and upper tiered bed structure. The present invention is adaptable to virtually all type of recreational vehicles as well as residential usage.